Analysis of information sources in references of the Wikipedia article "Modern Standard Arabic" in English language version.
…there is no chronological point at which CLA turned into MSA, still less any agreed set of linguistic criteria that could differentiate the two. MSA is merely a handy label used in western scholarship to denote the written language from about the middle of the nineteenth century, when concerted efforts began to modernize it lexically and phraseologically. Most western scholars refer to the formal written language before that date, and par excellence before the eclipse of Arab political power in the fifteenth century, as "Classical Arabic".